Theme Packaging

This document describes how to package themes for Firefox and Thunderbird.

Pre-requisites

Making a theme for Firefox or Thunderbird requires knowledge of Cascading Stylesheets (CSS), probably XBL, and some graphic design and aesthetic skill (...or maybe not). This document describes only how Themes are packaged in order to be shown in Firefox's Themes window.

Theme File Layout

Firefox/Thunderbird themes are packaged in an XPI file with the following structure:

You must have a top-level chrome.manifest file which registers the chrome for the theme (as before) and also an install.rdf manifest that specifies metadata that is displayed in the Appearance section of the Add-ons Manager.

preview.png is a preview image which will show when double-clicked on a theme in the Appearance section of the Add-ons Manager. It can be any size.

icon.png is a 32x32 (max. 48x48) PNG (may contain alpha transparency) which will show up in the Appearance section of the Add-ons Manager.